When a character's first line is "Dirt," you just know they're going to be unimportant.
We jest—sort of. C.W.'s importance to the plot of Bonnie and Clyde (and to the Barrow gang in general) comes in two flavors: loyalty and idiocy.
Let's deal with the latter first. C.W. not only has the affable face of a five-year-old, but he also seems to think like a five-year-old. He decides to parallel park while he's manning the getaway car during a robbery. He decides to flash his pistol when he's going to grab a few chicken dinners for the Barrow Gang hideout.
And, worst of all, he decides to take Bonnie and Clyde home to his less-than-approving daddy.
Sure, Bonnie and Clyde are wounded and bleeding when C.W. decides to get help from his paw-paw. But we really want to smack this kid over the head because, in the scene before, we see C.W. get help from a group of migrant farmers who completely idolize Bonnie and Clyde.
When C.W. gets water for B & C, the farmers gather around the car, muttering:
FARMERS: It's Bonnie and Clyde. What happened to them? Are they famous? Sure enough.
One of the farmers reaches out to touch Clyde's hand gently. A woman gives them some soup. These farmers care about Bonnie and Clyde, and we're guessing that C.W. could have easily asked them for some bullet-extraction tips.
But oh, no. He had to run home to his dad… who promptly makes a deal with a Texas Ranger to have Bonnie and Clyde offed, and C.W. jailed.
But our cherubic sidekick isn't just a dolt. He's also a loving, super-loyal dolt. Just look at the rousing speech his gives his father when Mr. Moss tells him that the Texas Rangers are planning a shoot-out:
C.W.: You think laws are going to catch Bonnie and Clyde in town? Clyde's got a sense. Don't you know that, Daddy? Nobody catches Clyde. Never. Never!
This is very, very sweet…and very, very untrue.
We see C.W.'s loyalty in other ways as well. He stands guard at Bonnie's depressing family reunion. He offers to drive Blanche to a chicken restaurant to relieve the tension in the crowded tourist cabin, and then asks her about her life.
And, as we see by the pained look on C.W.'s face as Bonnie and Clyde drive away to their certain death, he cares for them. He's a young kid who got in too deep… but he's a young kid with a good heart.